What kind of noun is Down Syndrome?

The noun Down syndrome is a proper, compound noun; a Word for a congenital disorder arising from a chromosome defect, a thing.

The condition is named for John Langdon Down who fist to publish the range of symptoms as a single disorder.

The common noun form 'syndrome' can be used for the condition, but the Word 'Down' must be capitalized as a proper noun, the name of the person and the name of the condition.